# capsulflask Python Flask web application for capsul.org ## how to run locally Ensure you have the pre-requisites for the psycopg2 Postgres database adapter package ``` sudo apt-get install python3-dev libpq-dev pg_config --version ``` Create python virtual environment and install packages ``` python3 -m venv .venv source .venv/bin/activate pip install -r requirements.txt ``` Run an instance of Postgres (I used docker for this, you can use whatever you want, point is its listening on localhost:5432) ``` docker run --rm -it -e POSTGRES_PASSWORD=dev -p 5432:5432 postgres ``` Run the app ``` FLASK_APP=capsulflask flask run ``` Run the app in gunicorn locally ``` pip install gunicorn .venv/bin/gunicorn --bind 127.0.0.1:5000 capsulflask:app ``` ## postgres database schema management capsulflask has a concept of a schema version. When the application starts, it will query the database for a table named `schemaversion` that has one row and one column (`version`). If the `version` it finds is not equal to the `desiredSchemaVersion` variable set in `db.py`, it will run migration scripts from the `schema_migrations` folder one by one until the `schemaversion` table shows the correct version. For example, the script named `02_up_xyz.sql` should contain code that migrates the database from schema version 1 to schema version 2. Likewise, the script `02_down_xyz.sql` should contain code that migrates from schema version 2 back to schema version 1. **IMPORTANT: if you need to make changes to the schema, make a NEW schema version. DO NOT EDIT the existing schema versions.** In general, for safety, schema version upgrades should not delete data. Schema version downgrades will simply throw an error and exit for now.